1. Technical Field
The present invention relates generally to cylinder liners for diesel engine applications, and more particularly to liners with protective coatings.
2. Related Art
Diesel engines are widely utilized for providing power for trucks, ships, and construction machines, as well as for use in electrical power generation. In an effort to abate air pollutants such as nitrogen oxides (NOx) present in exhaust gases produced by diesel engines, government regulations may soon require the recirculation of exhaust gases in diesel engines. An exhaust gas recirculation system (EGR) may be utilized as a means of controlling NOx emissions, but also produces an environment within the engine that is characterized by increased corrosive potential compared to a non-EGR combustion system. An EGR system increases the potential for the production of organic acids and other corrosive elements that could attack the usual coated and non-coated ferrous cylinder liners.
U.S. Pat. No. 4,706,616 discloses a cylinder liner that includes a coating of a wear and seizure resistant ceramic material and may not provide an adequate barrier to
U.S. Pat. No. 5,619,962 discloses an electroplated wear and seizure resistant coating for a cylinder.
It is therefore an object of the present invention to provide a ferrous cylinder liner that is protected against attack from an EGR environment in diesel engines.
A cylinder liner for a diesel engine having exhaust gas recirculation (EGR) includes a ferrous cylinder liner body having an inner surface. The inner surface is covered by a continuous, non-porous EGR coating of electroless nickel which presents a barrier to the EGR environment.
The cylinder liner has the advantage of providing a continuous electroless nickel barrier layer that does not require additional machining or finishing after the barrier layer has been applied. Because there is no additional machining, the coating remains continuous to protect the cylinder liner from the corrosive EGR environment.
The electroless coating can be applied in a uniform, thin layer such that the dimensional tolerances of the cylinder can be maintained without the use of further finishing operations after the coating has been applied. This arrangement allows for an economical corrosion resistant part to be produced without complex machining of the cylinder liner or the cylinder of a diesel engine to accommodate the thickness of a coating.